On one of the last shimmering days of summer, two weathered, middle-aged men undress in a parking lot on the northeastern shore of Lake Zurich. This is the city’s Gold Coast, where a halfway decent villa will set you back a couple of million francs. Jabbering in a Swiss dialect while working with swift, sure hands, the divers pull on thick black exposure suits and 20 kilograms of gear, including two big steel cylinders of pressurized breathing gas.

”It’s not always fun like this!” says one of the divers, a trim fellow with salt-and-pepper hair and a neatly trimmed beard. That’s Ernst Völlm. He lives on the shadier side of the lake. But he loves it here, where as a kid he used to swim, snorkel, and dream of being an underwater explorer like his idol, Jacques Cousteau.

For Völlm, today is a workday. On his left wrist he’s wearing his latest creation, an advanced dive computer known, appropriately enough, as the Zurich Scuba Diver Assistant, or SDA. He and his jovial dive buddy, Georges Götte, waddle web-footed down to the water, joking with nearby swimmers. Götte calls out ”Gute Luft” (”good air”), and they jump in feet first. As Völlm descends into the blue depths, he clutches a rack of SDAs. Twenty minutes later, the divers resurface, and Völlm’s rack is chirping like a field of crickets. To test the units, he had ”tricked” them into thinking he’d dangerously exceeded safety limits, and they are all screeching in protest.

Völlm is chief technology officer for Underwater Equipment Made in Switzerland, or UEMIS, headquartered in Adliswil. The 5-year-old firm’s offering is already among the world’s most coveted dive computers. Like any such unit, the SDA records the diver’s depth and time underwater and uses that data to calculate, every few seconds, whether it’s safe to return to the surface. If it’s not, the computer calculates a decompression schedule—basically an ascent plan that will let the diver get back to the world of air and light without risking a case of decompression sickness, better known as the bends.

Völlm built his first piece of diving gear—a diving lamp (”a car light in a housing, more or less”)—when he was 20. At the time he was studying mechanical engineering at the Swiss Federal Institute of Technology. His first job was at a yarn-winding company, where he worked on an electronic bobbin winder.

Meanwhile, he was training to be a diving instructor and helping to establish the Swiss Office for the Prevention of Diving Accidents. Switzerland may be landlocked, but it’s a diver’s paradise. The country’s gin-clear mountain lakes offer trout, distinctive underwater landscapes, and for part of the year, through-the-looking-glass views of surface ice. But the low air pressure at high altitudes complicated the calculations that divers had to do to minimize their risk of the bends. The tediousness and precariousness of the chore got Völlm thinking about how microprocessors could do it better.

In 1987, Völlm and Markus Mock, an engineer friend, founded their own company, Dynatron, and designed the hardware and software for a dive computer that was manufactured and marketed by Uwatec, a diving equipment maker based in Hallwil, Switzerland. That first computer did well, selling upward of 100 000 units all over the world. Other models followed, including a type known as a console unit: A high-pressure hose attached it to the diver’s air tank so that he could see, in one place and in real time, all the critical information related to the dive—his depth, total time underwater, how much longer he could stay down without risking a case of the bends, the temperature, and most important, the tank’s pressure.

It was the beginning of a 17-year relationship with Uwatec that ended in 2004, seven years after the firm was bought out by the American firm Johnson Outdoors. Sometime later, another of Völlm’s diving buddies, Lukas Metzler, got Völlm and Mock to join him in starting a company to create a state-of-the-art dive computer. It would be worn on the diver’s wrist and get pressure readings from the tank via a wireless link. But whereas other computers allow the diver to see only his own data, Völlm and Mock’s would be part of an ad hoc network. Instead of swimming to your dive buddy to read how much air he had left, you could check it on your own unit. The computer would also interface with the Internet via a PC hookup to upgrade software or synchronize log data with a Web-based logbook, for example.

They tested their first two prototypes in January 2008 in Lake Zurich, in witheringly frigid water. Völlm and Metzler, now the company’s CEO, each went under with one of the gadgets, only to have the prototypes’ plastic casing crack from the cold. ”But they were still watertight, and we could make the tests,” Völlm recalls proudly. Many other test dives followed. With its organic-LED display, the current-generation SDA is a marvel of diving technology, with a price tag to match: US $1600, or 1120. It stores details on up to 2000 past dives and also allows multiple divers to communicate underwater.

The units arrive at UEMIS semifinished from a factory elsewhere in Switzerland. Technicians check pressure resistance and function by exposing the SDAs to a simulated saltwater environment. The ruggedness test is simple but effective—they’ll occasionally throw one down a flight of stairs.

As CTO of UEMIS, Völlm describes his job as ”everything except maybe the finances.” Lately, he’s been globe-hopping to promote the product. The company has seven full-time employees; Völlm insists that they all pass a basic diving course so that they’ll better understand the product they make. Anyone with a technical and scientific bent can’t help but be intrigued by dive computers, Völlm says, because the design and operation of these tiny but powerful computers pulls together so many fascinating disciplines: medicine and physiology, electronics, software and modeling, mechanics, and physics.

When Völlm was in industry, he knew he wanted more responsibility—and especially more risk. As an entrepreneur, he’s found it. There are times when he feels a bit overwhelmed by the responsibilities, he concedes. But that’s when he can go back to the place that fueled his dreams as a boy—where he can pull on a thick diving suit and remind himself how much fun it can be to really be in over your head.

This article originally appeared in print as "Rapture of the Deep."

About the Author

Giselle Weiss is a freelance writer based in Basel, Switzerland. In Dream Jobs, she profiles Ernst Völlm, who designs and field-tests advanced dive computers. “I worried that I’d have to go diving in Lake Zurich with Ernst,” says Weiss. Happily, she didn’t have to. Instead, she drank in the late afternoon sun while Völlm and a buddy dropped their clothes in the parking lot and suited up.